1. Field of the Invention
The present invention relates to a physiological signal detection module, a multi-channel connector module and a physiological signal detection apparatus using the same, capable of detecting a stable physiological signal without distortion. The physiological signal detection module has a heating member and a multi-channel connector. The heating member maintains an electrode's contact with a user skin at a constant temperature, and the multi-channel connector module for electrical connection transmits the physiological signal, which is detected from the electrode, to an external physiological signal detection apparatus.
2. Discussion of Related Art
In general, an electrode is attached to a user skin of a subject to measure a physiological signal. A typical electrode is a disposable electrode, e.g., a wet electrode. To reduce impedance between the user skin and the electrode, a conductive gel is applied to the metallic electrode, thereby facilitating converting ion current flowing in a living body into an electric current.
However, the disposable electrode using the conductive gel incurs a skin trouble such as a reddish skin and stinging pain, when used for a long-time measurement. Therefore, it is somewhat difficult to use the disposable electrode in the portable physiological detection apparatus that monitors the physiological signals for a long-time.
Accordingly, there has been proposed a method of using a dry electrode rather than the conductive gel, which is suitable to measure the physiological signal for a relatively long time. The dry electrode uses a conductive polymer or metal having good conductivity. However, there are problems in that the physiological signal is distorted due to difference of impedance between the user skin and the dry electrode, and it is possible to get the stable physiological signal only after a predetermined time elapses from when the dry electrode is attached to the user skin.
To solve the afore-mentioned problems, a method of placing a buffer as close as possible to the dry electrode to match the impedance was proposed. Conventionally, the buffer is placed at a connector portion of the dry electrode, and a power is connected to the physiological signal detection apparatus using an independent cable. This is referred to as an active electrode. However, the active electrode has problems in that its connector should be designed such that the power can be supplied from the physiological signal detection apparatus to the active electrode through the connector.
To solve the afore-mentioned problems, several technologies have been proposed. For instance, U.S. Pat. No. 4,865,039 entitled to “Dry electrode system for detection of biopotentials and dry electrode making electrical and mechanical connection to a living body” discloses a system in which the connector includes a circuit for amplifying physiological signals and a battery pack for supplying power to an amplification circuit is mounted to the connector connected with the measurement apparatus.
However, in the foregoing conventional technology, the battery pack for supplying power is required for each of the dry electrodes, so that the multi-channel system becomes complicated and expensive.